This invention relates to a semiconductor memory device, and a redundancy system and a layout system therefor. More particularly, it relates to techniques which are effective when utilized for, for example, a multi-port (dual-port) memory having a random input/output port and a serial input/output port.
A multi-port memory having both a random access port and a serial access port is stated in, for example, "NIKKEI ELECTRONICS", pp. 243-264 issued on Mar. 24, 1986 by Nikkei McGraw-Hill Kabushiki-Kaisha.
With the progress of computer graphics, the development of a multi-port memory of enlarged storage capacity and heightened operating speed is requested for the color display of high resolution.